Monoethylene glycol is used as a raw material in the manufacture of polyester fibres, polyethylene terephthalate (PET) bottles and resins. It is also incorporated into automobile antifreeze liquids.
Monoethylene glycol may be prepared in a highly selective process from ethylene oxide via ethylene carbonate. This is typically carried out in a two-step process wherein the first step is the reaction of ethylene oxide with carbon dioxide to form ethylene carbonate, and the second step is the hydrolysis of ethylene carbonate to form ethylene glycol.
Catalysts may be supplied to the carboxylation and hydrolysis steps to increase both the rate and selectivity of the reaction. WO 2007/144360 discloses a process for the manufacture of alkylene glycol from alkylene oxide via alkylene carbonate, wherein homogeneous carboxylation and hydrolysis catalysts are used. A homogeneous catalyst solution (comprising carboxylation catalyst and hydrolysis catalyst) is separated from crude monoethylene glycol and is recycled back to the carboxylation and hydrolysis reactors.
The present inventors have sought to further improve the manufacture of alkylene glycol from alkylene oxide.